I would guess it would be pretty rare for the change to go so far as producing sperm. I still wouldn't really call that transgender.I found a little article on "transgender" ducks here if you are interested in learning more.
https://www.bbc.com/news/science-environment-40016817
I thought it was pretty interesting
Like the article said there is something medically going on there.
And the duck did not live long once things progressed for the worse.
Drakes have a penis. Chickens do not.
Even if a duck could start producing sperm it would be unlikely it would be able to fertilize anything without the appendage.
Maybe not *impossible* but highly unlikely.